There are several difficulties associated with transferring fluids or gases such as oil, natural gas or air, across a body of water. As has been demonstrated, tanker ships are costly to operate, impractical for transporting small distances and potentially hazardous to the environment. Furthermore, laying pipelines across the surface of a body of water is clearly not a solution, as these above-water pipelines would pose significant obstacles to water traffic and also produce a great deal of noise. Similarly, pipelines permanently anchored to the bottom of the body of water are costly to install and even more costly to maintain and/or repair, requiring expensive deep sea welding to repair leaks.
However, there are several potential uses for underwater pipelines, such as, for example, transmitting gases and liquid hydrocarbons from off-shore gas and oil wells, super tanker loading and unloading in shallow or environmentally sensitive areas where regular port facilities are unavailable, and natural gas pipelines across oceans, lakes and rivers.
Similarly, the aeration of lakes and treatment of waste water is more effectively done by injecting compressed air into the body of water from beneath the surface of the body of water, that is, by an underwater aeration system. Specifically, using this method, no aerosols are produced which may be harmful and there is little noise produced. However, as with the fluid-transfer pipelines, these sub-surface aeration pipelines are costly to maintain and/or repair. The prior art discloses several methods and devices that attempt to overcome this problem:
U.S. Pat. No. 4,273,732 teaches an apparatus for raising a liquid aeration apparatus. The apparatus comprises a carrier element which is guided by a guide device connected to boom arranged for engaging air distributing pipes beneath the surface of a body of water. This device is limited in that the location of the air distributing pipes must be known or visible in order for the pipes to be brought to the surface and a large boat must be used to support the boom. Finally, the device can only lift one section of the air distributing pipe at one time, making routine maintenance of the aeration system time consuming and expensive.
U.S. Pat. No. 5,587,114 teaches an aeration system comprising a main air supply pipe arranged to float on the surface of a body of water which is provided pressurized air via a blower. Flexible hoses decend downward from the air supply pipe and are connected to a plurality of submerged conduits, the conduits each including a plurality of air diffusers. Thus, the device includes a plurality of modules comprising two flexible hoses and a conduit including a plurality of air hoses each connected to the main air supply pipes. In one embodiment, each module is connected to a ballast block by a flexible line that is also connected to the main air supply such that the individual module may be brought to the surface by pulling on the flexible line. In an alternative embodiment, each module includes an inflatable bladder for bringing each individual module to the surface as desired. While in these arrangements, no heavy equipment is needed to bring the individual modules to the surface, it is limited in that each individual module is raised individually, thereby making routine maintenance time consuming. Furthermore, this device is poorly suited for aerating lakes and the like, as the main air supply pipe lies on the surface of the lake, thereby interfering with lake traffic and producing considerable noise.
U.S. Pat. No. 5,690,864 teaches an aeration system for a wastewater treatment plant. The device comprises an air supply pipe for receiving compressed air arranged to float on the surface of the lagoon. Flexible air supply conduits decend downward from the air supply pipe and are each connected at one end to an elongate aerator. Guide members are provided for fixing the location of the elongate aerators relative to the flexible air supply conduits and the bottom of the wastewater basin. As with the above-described, this device is limited in that only one section of the device can be brought to the surface at one time and the device would be poorly suited for aerating lakes and the like as the main air supply pipe would lie across the surface of the lake.
The limitations and inherent difficulties associated with the prior art devices clearly indicate that a method is needed for transporting fluids across a body of water and for aerating bodies of water that is easy to install and service.